All comes down to what, very specifically, you need YOUR (meaning, not mine, not the other guys in the forum) 85mm lens to do.

I sold my 85/1.4 AFD long ago because I needed a lens that was sharper wide open for theater/dance work (where the 1.8G is superior) and also sharper for long distance landscape work, where the AFD was also weaker than any other 85mm option, zoom or prime, I had at the time (the 85/1.8G is definitely and clearly superior at landscape distances at any aperture). So in my case, it was a no brainer. You couldn't give me an AFD for free today. I would have no use for it. BUT - on the other side of the argument - the AFD is famous for reason - in short distances for portraiture work around F/2 - F/2.8, there is little better. It's awesome in this regard, positively awesome. Note how I didn't use this lens for portrait work at these apertures and distances, so it wasn't a fit for ME, which is why my opinion may or may not line up with others on this lens. So someone who wants a classic, older school rendering portrait lens (fairly sharp center, intentionally blurred edges and excellent bokeh) with a cooler color rendering (compared to newer "G" lenses) and shoots almost always in the closer distance ranges where the 85/1.4 AFD excelled would be better off staying put - the new lens would be a step down here. Someone who places more value on sharpness at longer distances (as well as still being very sharp at shorter distances) and better F/1.8 - F/2.8 performance in terms of lack of veiling flare and better crispness/contrast who uses it for rock concerts, stage/theater/dance and does NOT value bokeh as highly or does NOT shoot wide or near wide open portraiture would be better suited to the newer 1.8G lens. In some ways you could say the older AFD was a portrait specialist lens while the 1.8G is a general purpose lens that while not the absolute best at classic, old school portraiture, is likely a better fit for a wider range of subject matter. The older AFD had a more distinctive rendering style due to it's specialty nature, while the newer 1.8G is fairly neutral in rendering - it's not going to suddenly impart some magical pixie dust upon your images as it's designed to do a lot of things very well. Different design intents. Thus, someone who really liked 85mm lenses and used that focal length a lot might very well have BOTH. Someone who REALLY liked 85mm lenses might have all 3 !!! (1.4 AFD, 1.4G AFS, and 1.8G). The only lens I'd specifically NOT recommend is the 85/1.8 AFD, which has some known issues with aperture blade reflection with digital sensors at and beyond F/11 in high key scenes.

So the answer comes down to what you value most and what distances you shoot.

-m

Disclaimer: Owned the 85/AFDs (both 1.8 and 1.4 versions) for 7+ years prior to selling them, currently own the 85/1.8G AFS, and have shot/evaluated the excellent 85/1.4G AFS as well.